Gastroenterology

Gastroenterology

Volume 150, Issue 6, May 2016, Pages 1292-1304.e2
Gastroenterology

Section I: FGIDs: Background Information
Physiology
Fundamentals of Neurogastroenterology: Physiology/Motility – Sensation

https://doi.org/10.1053/j.gastro.2016.02.030Get rights and content

The fundamental gastrointestinal functions include motility, sensation, absorption, secretion, digestion, and intestinal barrier function. Digestion of food and absorption of nutrients normally occurs without conscious perception. Symptoms of functional gastrointestinal disorders often are triggered by meal intake, suggesting abnormalities in the physiological processes are involved in the generation of symptoms. In this article, normal physiology and pathophysiology of gastrointestinal function, and the processes underlying symptom generation, are critically reviewed. The functions of each anatomic region of the digestive tract are summarized. The pathophysiology of perception, motility, mucosal barrier, and secretion in functional gastrointestinal disorders as well as effects of food, meal intake, and microbiota on gastrointestinal motility and sensation are discussed. Genetic mechanisms associated with visceral pain and motor functions in health and functional gastrointestinal disorders are reviewed. Understanding the basis for digestive tract functions is essential to understand dysfunctions in functional gastrointestinal disorders.

Section snippets

Normal Physiology: Main Components

The fundamental gastrointestinal functions include sensation, motility, digestion, absorption, and secretion.

Food, Meal Intake, and Microbiota

The meal ingested is transformed from the mouth to the ileum, first by digestion and then by absorption, so that only nonabsorbed residues pass into the colon. The whole digestive–absorptive process down to the terminal ileum is finely regulated depending on the composition of intraluminal content; nutrients in the stomach and small bowel have limited effects on colonic activity. Nonabsorbed meal residues entering the colon serve as substrate to feed microbiota and this interaction has several

Genetics

Genetic mechanisms appear to be associated with visceral pain and motor functions in health and functional gastrointestinal disorders. Familial aggregation and twin studies support a genetic factor in IBS. In addition, gene variations have been described in association with the symptom phenotype of IBS, biomarkers of visceral pain, and motor function.

Esophageal motility and lower esophageal sphincter function

The coordinated motor pattern of the esophagus initiated by the act of swallowing is called primary peristalsis. Primary peristalsis usually clears most contents of the esophagus into the stomach. Secondary peristalsis is provoked by residual food or reflux events, and it is not accompanied by pharyngeal contraction or upper esophageal sphincter relaxation. Peristalsis in the striated muscle part of the esophagus is dependent on central vagal pathways. It is mediated by sequential excitation of

Concluding Remarks

Understanding the basis for digestive tract functions is essential to understand dysfunctions in the functional gastrointestinal disorders. This article has discussed and critically assessed the normal physiology and pathophysiology, and the processes underlying symptom generation. From this careful review, the following recommendations for future research in this area emerge.

  • Define new characteristics of wall function other than phasic and tonic contractions (eg, longitudinal muscle

References (50)

  • Y. Norimatsu et al.

    Lubiprostone activates CFTR, but not ClC-2, via the prostaglandin receptor (EP(4))

    Biochem Biophys Res Commun

    (2012)
  • B.S. Wong et al.

    Increased bile acid biosynthesis is associated with irritable bowel syndrome with diarrhea

    Clin Gastroenterol Hepatol

    (2012)
  • J. Serra et al.

    Lipid-induced intestinal gas retention in irritable bowel syndrome

    Gastroenterology

    (2002)
  • G.D. Wu et al.

    Analysis of the human gut microbiome and association with disease

    Clin Gastroenterol Hepatol

    (2013)
  • A. Morris-Yates et al.

    Evidence of a genetic contribution to functional bowel disorder

    Am J Gastroenterol

    (1998)
  • R.L. Levy et al.

    Irritable bowel syndrome in twins: heredity and social learning both contribute to etiology

    Gastroenterology

    (2001)
  • S.J. Brookes et al.

    Extrinsic primary afferent signalling in the gut

    Nat Rev Gastroenterol Hepatol

    (2013)
  • E.A. Mayer

    Gut feelings: the emerging biology of gut-brain communication

    Nat Rev Neurosci

    (2011)
  • L. Van Oudenhove et al.

    The role of psychosocial factors and psychiatric disorders in functional dyspepsia

    Nat Rev Gastroenterol Hepatol

    (2013)
  • D. Keszthelyi et al.

    Irritable bowel syndrome: methods, mechanisms, and pathophysiology. Methods to assess visceral hypersensitivity in irritable bowel syndrome

    Am J Physiol Gastrointest Liver Physiol

    (2012)
  • C.H. Wilder-Smith

    The balancing act: endogenous modulation of pain in functional gastrointestinal disorders

    Gut

    (2011)
  • S. Elsenbruch et al.

    Affective disturbances modulate the neural processing of visceral pain stimuli in irritable bowel syndrome: an fMRI study

    Gut

    (2010)
  • K. Tillisch et al.

    Advances in imaging the brain-gut axis: functional gastrointestinal disorders

    Gastroenterology

    (2011)
  • S.K. Sarna

    Myoelectrical and contractile activities of the gastrointestinal tract

  • E. Distrutti et al.

    Rectal function and bowel habit in irritable bowel syndrome

    Am J Gastroenterol

    (2004)
  • Cited by (100)

    • Understanding small intestinal dysmotility symptoms: Bloating, distension, and gas

      2023, Handbook of Gastrointestinal Motility and Disorders of Gut-Brain Interactions, Second Edition
    • Intestinal transit disorders

      2024, Gastroenterologie
    View all citing articles on Scopus

    Conflicts of interest The authors disclose no conflicts.

    View full text